I once listened to an interview with Todd Barry (who also participated) on the radio station WFMU, and he basically confirmed this (though he was reluctant to talk about it - the host pressured him a bit). He also said, if I remember correctly, that the Friars people had trouble getting anyone from the original Saturday Night Live to attend.
I read about that in an article in EW interviewing CC, so he was pretty plain about how hurt he was by the hostility. Paul Shaffer spent the evening having to try and talk him down.
See, I can never understand why celebrities agree to these roasts and then get upset, hurt or mad at the jokes made. They know full well what they're letting themselves in for.